### This comment letter response contains two parts:

(1) The original submittal from the commenter.

(2) A data base printout of EPA’s response to each point raised by the commenter.

Notes about the response letters:

• The response letters were generated by a data base used to track the content of all public

comment submittals and ensure that the Agency responds to each. Each comment letter

was assigned a Letter ID that corresponds to the last four digits of the docket number of the

original comment (as posted on www.regulations.gov).

• Each response letter includes: comment text; an EPA

‐ assigned comment code; and an

individual response. These are described and explained below.

• The data base contains Comment text from the letters submitted by commenters.

Many hard copy letters were scanned into electronic format for inclusion in the data

base. As a result, there may be some typographical errors attributable to optical

character recognition issues. However, all original submittals were reviewed in the

process of drafting responses to ensure that the comment content was understood and

appropriately addressed.

• The content of each comment letter was divided into topic areas and assigned a unique

Comment ID. Additionally, one or more Comment Codes (i.e., unique topic area ID) was

assigned to each discrete point raised by a commenter. This information was added to

the data base. To inform final rulemaking decisions, all comments and information

received on a given topic were reviewed by technical experts in each rule area (e.g., on

construction requirements).

• Following decisions on the final rule requirements, Individual responses were drafted

by topic area to ensure completeness and consistency of the responses with the final

rule and other responses to similar comments. Each discrete point made by a

commenter was given a unique response.

• Upon completion of comment responses, all information was entered into the data base.

Each letter response is a compilation of each comment and its individual response,

compiled in the order of the original comment letter. As a result of this process, there is

repetition in the response text. The Agency believes this approach ensures completeness

and attention to each comment letter that was submitted.

• All comments in a topic area were reviewed, evaluated, and responded to concurrently.

Responses on each topic area are compiled and are also available in the rulemaking docket.To: United States Environmental Protection Agency (EPA)

From: Kenneth J. Nemeth, Executive Director and Secretary, Southern States Energy Board

Principal Investigator, Southeast Regional Carbon Sequestration Partnership

Date: December 23, 2008

Re: Docket ID No. EPA–HQ– OW–2008–0390, Comments on 40 CFR Parts 144 and 146 Federal

Requirements Under the Underground Injection Control (UIC) Program for Carbon Dioxide

(CO

2 ) Geologic Sequestration (GS) Wells; Proposed Rule

The Southern States Energy Board (SSEB) serves to enhance economic development and the quality of

life in the South through innovations in energy and environmental policies, programs and

technologies. Sixteen southern states and two territories comprise the membership of SSEB.

Representative of our efforts, SSEB manages the Southeast Regional Carbon Sequestration

Partnership (SECARB), a research program established in 2003 with the primary goals of identifying

major sources of carbon emissions, characterizing the geology of a 13

‐ state region, determining the

most promising options for commercial deployment of carbon sequestration technologies in the

South, and validating the technology options through carefully executed field testing. SECARB is one

of seven regional carbon sequestration partnerships nationwide, co

‐ funded by the United States

Department of Energy. SECARB’s membership is comprised of more than 100 active industry,

government, academic, and non

‐ profit participants.

Regarding injection issues, our areas of common interest within the partnership include:

• aquifer exemptions and prohibition on injection above underground sources of drinking

water (USDWs) (e.g. coal seams);

• credit for storage in enhanced oil recovery (EOR)

‐ related applications; and

• transitioning from Class II EOR activities to storage only.

SSEB offers the following comments, which represent a consensus of thoughts shared by many of the

SECARB technical partners and stakeholders.

The proposed Federal requirements under the Safe Drinking Water Act (SDWA) for underground

injection of carbon dioxide for the purpose of geologic sequestration is a step forward. SSEB supports

the establishment of a new Class VI designation specifically dealing with GS. A new class of wells with

minimum technical criteria for the geologic site characterization, fluid movement, area of review

(AoR) and corrective action, well construction, operation, mechanical integrity testing, monitoring,

well plugging, post

‐ injection site care, and site closure for the purposes of protecting USDWs will

advance GS projects. The proposed rule will help to ensure consistency in permitting of underground

injection of CO 2 at GS operations across the United States and provide requirements to prevent

endangerment of USDWs in anticipation of the eventual use of GS to reduce CO 2 emissions. EPA’s

regulatory provisions should accurately reflect the low risk profile that exists for CO 2 exposure from a

GS project.SSEB

Comments on EPA Proposed Rule, Docket ID No. EPA–HQ–OW–2008–0390 2

Importantly, under the proposed rule, EPA should specify that CO 2 is not considered hazardous, nor

subject to regulation under RCRA or CERCLA, (while the rule recognizes that other gases could

contaminate the CO 2 , resulting in hazards to USDWs). Equally important, there should not be

limitations on formations that could be used for GS nor any depth limitations on injection zones. SSEB

does not support limiting a GS project beneath a sole source USDW aquifer or above the lowermost

USDW. These restrictions would only serve to limit a GS project from being sited in what would

otherwise be very safe geology. SSEB also does not support the requirement of secondary seals for

the same reason as stated above. The only requirement would be viable provisions for safe and

secure containment to protect USDWs.

“Tailored requirements,” as opposed to more general or more specific requirements, are preferable

as they provide adequate protection while simultaneously allowing for the flexibility to address local

geology and site

‐ specific conditions and to embrace evolving technology. Tailored requirements

should be brought to bear when considering the nine specific topical areas for addressing the

proposed Class VI UIC requirements:

1. Geologic Siting;

2. Area of Review and Corrective Action;

3. Injection Well Construction;

4. Injection Well Operating;

5. Mechanical Integrity Testing;

6. Plume and Pressure Front Monitoring;

7. Recordkeeping and Reporting;

8. Well Plugging, Post

‐ Injection Site Care, and Site Closure; and

9. Financial Responsibility and Long

‐ term Care.

Regarding specific points, we concur with the establishment of a threshold of a seabed up to three

miles offshore, but no farther, and we support a requirement that the project operator should be able

to demonstrate that the CO 2 is contained within the storage zone. We do not support the need to

monitor the exact location with in

‐ zone monitoring wells, the CO 2 plume, or displace brine pressure

front. CO 2 monitoring should be fit for purpose. Air and soil gas monitoring is unlikely to be

beneficial, and the use of tracers should be at the discretion of the owner/operator.

Injection well construction details should be consistent with Class II CO 2 EOR experiences and

operations and not unnecessarily burdensome to an owner/operator of a GS project. Continuous

cementation from base to surface of the long

‐ string casing should not be required. No specific

timeframe for post closure care should be specified, and it should be based on performance standards

demonstrated by the owner/operator. Corrosion monitoring is unnecessary, as it would be assumed

that compatible well construction materials suitable for use with site

‐ specific CO 2 composition would

be consistent.

It is not useful to arbitrarily limit the depth of coal seams, since coal seams store CO 2 via a very

different mechanism such that the required pressures are only a few hundred pounds per square inch

(psi) instead of many hundreds or thousands of psi. The Southeast contains numerous oil and gas

fields that are potential safe geologic storage sites. SSEB encourages EPA to adopt a reasonableSSEB

Comments on EPA Proposed Rule, Docket ID No. EPA–HQ–OW–2008–0390 3

process for EOR sequestration within Class II and EOR crossover to sequestration in oil and gas fields.

Oil and gas fields are proven geologic sinks and contain much of the needed infrastructure for

efficient sequestration.

Finally, it is important to note that there are other issues, such as liability, that are crucially important

to GS and which can impact GS projects, which are not covered under this proposed rule and

program.

Thank you for the opportunity to provide comments on the Proposed Rule. We would be glad to

provide additional input as you require.

### Letter ID: 0176

Commenter: Kenneth Nemeth

Organization: Southern States Energy Board

Letter ID: 0176 Comment ID: 23534 Letter Lines: 35 to 55

Comment Code: 1000 1. General and Administrative Comments

Comment: Representative of our efforts, SSEB manages the Southeast Regional Carbon

Sequestration Partnership (SEC ARB), a research program es tablished in 2003 with

the primary goals of identifying ma jor sources of carbon emissions,

characterizing the geology of a 13-state region, determining the most promising

options for commercial deployment of car bon sequestration technologies in the

South, and validating the technology opti ons through carefully executed field

testing. SECARB is one of seven regional carbon sequestration partnerships

nationwide, co-funded by the United Stat es Department of Energy. SECARB’s

membership is comprised of more than 100 active industry, government, academic,

and non-profit participants.

Regarding injection issues, our areas of common interest within the partnership

include:

- aquifer exemptions and prohibition on injection above underground sources of

drinking water (USDWs) (e.g. coal seams);

- credit for storage in enhanced oil r ecovery (EOR)-related applications; and

- transitioning from Class II EO R activities to storage only.

SSEB offers the following comments, wh ich represent a consensus of thoughts

shared by many of the SECARB techni cal partners and stakeholders.

Individual Response: EPA acknowledges the comment. Pleas e see the remainder of EPA's

responses to this comment for further deta ils. For additional information on EPA's final

regulatory approach, please see the final rule and preamble, including th e discussion of aquifer

exemptions and the repermitting of Class II/EOR wells for GS, as well as the rulemaking docket.

EPA clarifies that carbon crediting and green house gas accounting are outside the scope of the

UIC GS rulemaking. The Class VI GS rule is designed to ensure consistency in permitting

underground injection of CO2 at GS operations across the United States and provide

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to

reduce CO2 emissions.

Letter ID: 0176 Comment ID: 23535 Letter Lines: 57 to 69

Comment Code: 1210 1.1.1 Comments about the proposed rule

Comment Code: 2020 1.5.1 Support Class VI designation

1

### Comment: The proposed Federal requirements under the Safe Drinking Water Act (SDWA) for

underground injection of carbon dioxide for the purpose of geologic

sequestration is a step forward. SSEB supports the establishment of a new Class

VI designation specifically dealing with GS . A new class of wells with minimum

technical criteria for the geologic site characteriza tion, fluid movement, area

of review (AoR) and corr ective action, well construc tion, operation, mechanical

integrity testing, monitoring, well plugging, post-injection site care, and site

closure for the purposes of protecting USDWs will advance GS projects. The

proposed rule will help to ensure consistency in permitting of underground

injection of CO2 at GS operations ac ross the United States and provide

requirements to prevent endangerment of US DWs in anticipation of the eventual

use of GS to reduce CO2 emissions. EPA’s regulatory provisions should accurately

reflect the low risk profile that exists for CO2 exposure from a GS project.

Individual Response: EPA agrees that tailored requirements for Class VI wells are necessary to

address the unique nature of in jecting large volumes of CO2 a nd to ensure that USDWs are

protected from endangerment. The GS rule c ontains tailored requirements for the permitting,

geologic site characterization, AoR and corre ctive action, well construction, operation,

mechanical integrity testing, monitoring, well plu gging, post-injection site care, and site closure

of GS wells that directly addre ss issues unique to the nature of large-scale CO2 injection for GS.

Letter ID: 0176 Comment ID: 23537 Letter Lines: 71 to 74

Comment Code: 1630 1.3.3 RCRA/hazardous waste i ssues (seeking comment)

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment)

Comment: Importantly, under the proposed rule, EPA should specify that CO2 is not

considered hazardous, nor subj ect to regulation under RCRA or CERCLA, (while the

rule recognizes that other gases could c ontaminate the CO2, resulting in hazards

to USDWs). Equally important, there should not be limitations on formations that

Individual Response: EPA received many comments regardi ng the applicability of the RCRA

regulations and statute to CO2 st reams that are geologically seque stered under the final Class VI

UIC well requirements. As a result, EPA has deci ded to initiate a sepa rate proposed rulemaking

specifically to examine the issue of RCRA appl icability to CO2 streams being geologically

sequestered, including the possible option of a conditional exemption from the RCRA

requirements for CO2 GS in Class VI wells. EPA will consider these comments as part of its

development of that proposal. The Agency will consider issues pa rticular to RCRA in the context

of that separate rulemaking, and recommends that the commenter read that proposed rule when it

is published. The Agency notes that comment ers who wish to submit comments on the RCRA

proposal will need to do so during the comment pe riod for that rule. Finall y, EPA also notes that

the final GS rule, which adds ne w regulations for Class VI wells under the Safe Drinking Water

Act (SDWA), is not making any changes to the RCRA regulations.

With respect to CERCLA, EPA clarifies that CO 2 itself is not listed as a hazardous substance

2

### under CERCLA; however, the CO2 stream may cont ain a listed hazardous substance (such as

mercury) or may mobilize substances in the s ubsurface that could react with ground water to

produce listed hazardous substances (such as sulf uric acid). Whether such substances may result

in CERCLA liability from a sequestration facili ty depends entirely on the composition of the

specific CO2 stream and the environmental medi a in which it is stored (e.g., soil or ground

water). CERCLA exempts from liability, under CERCLA section 107, 42 U.S.C. 9607, certain

“federally permitted releases” (FPR) as defined in CERCLA, 42 U.S.C. 9601(10). Class VI

permits will need to be carefully structured to ensu re that they prevent potential releases from the

well which are outside the scope of the Class VI permit.

Letter ID: 0176 Comment ID: 23538 Letter Lines: 74 to 75

Comment Code: 2100 1.6 Target Geologic Formations for GS

Comment Code: 4344 2.4.4.2.2 Comments opposed to setting a minimum injection depth

Comment: to USDWs). Equally important, there should not be limitations on formations that

could be used for GS nor any depth limitati ons on injection zones. SSEB does not

Individual Response: EPA clarifies that the GS rule does not categorically prec lude injection of

CO2 into any non-USDW formation types. The purpose of the GS rule is to ensure protection of

USDWs from endangerment, and the rule requires that owners or operators demonstrate that

wells are sited in suitable systems with geologic formations to receive and confine injected CO2,

required at §146.83 of the GS rule. The Cla ss VI siting, well cons truction and operation,

monitoring and testing, and post-inj ection site care and site closur e requirements are designed to

ensure that injected CO2 remains within the target formation. If an owner or operator can

demonstrate to the Director's satisfaction that GS in coal seams, basalts, salt domes, or shales can

be accomplished in a manner that protects USDWs a nd meets all of the requirements of the GS

rule, the project may be permitted as a Class VI well.

EPA agrees that it is not appr opriate to set a minimum inject ion depth for GS projects. EPA

believes that a determination of site-suitability for GS (i.e., that subsurface formations will

receive and confine injected CO 2) should be made on a site-specific basis. The GS rule, at

§146.82, requires the owner or operator to prov ide extensive site- and project-specific

information to the Director to demonstrate that the site meets the minimum site criteria at

§146.83, that the CO2 will be contained within the injection formation, a nd that USDWs will be

protected from endangerment.

EPA acknowledges that there are limited circum stances where injectio n above the lowermost

USDW can be performed in a manner that protec ts USDWs, as long as appropriate protections

are in place. The final GS rule at §146.95 establis hes a process by which owners or operators can

seek a waiver of the Class VI injection de pth requirements for in jection into non-USDW

formations above and/or between USDWs. The waiver approach requires the submission of

extensive, site-specific information (in conjunc tion with the permit appl ication submission) to

demonstrate that injection of CO2 into a non-US DW that is above or between USDWs can be

done in a manner that is protective of USDWs. Th e requirements are designed to ensure that the

owner or operator, the Director, and the Regional Administrator cons ider, on a site specific basis,

3

### the implications, benefits, and challenges associat ed with GS and ensuring water availability and

USDW protection. For additional information on the waiver approach, please see the final rule

and preamble, as well as EPA's responses to comments on the Notice of Data Availability and

Request for Comment.

Letter ID: 0176 Comment ID: 23539 Letter Lines: 75 to 78

Comment Code: 4324 2.4.4.1.2 Comments opposed to requiring injection below the lowermost

USDW

Comment: could be used for GS nor any depth limitati ons on injection zones. SSEB does not

support limiting a GS project beneath a sole source USDW aquifer or above the

lowermost USDW. These restrictions would only serve to limit a GS project from

being sited in what would otherwise be very safe geology. SSEB also does not

Individual Response: EPA acknowledges that there are lim ited circumstances where injection

above the lowermost USDW can be performe d in a manner that protects USDWs from

endangerment, as long as appropriate protections are in place. The final GS rule at §146.95

establishes a process by which owne rs or operators can seek a waiv er of the Class VI injection

depth requirements for inject ion into non-USDW formations above and/or between USDWs.

Additionally, the final GS rule doe s not categorically preclude or prohibit injection into any type

of formation.

EPA believes that these requirements will ensure USDW protection while providing flexibility to

UIC program Directors and owne rs or operators who undertak e CO2 injection for GS. The

Agency believes this approach: 1) responds to co ncerns about local and re gional geologic storage

capacity limitations imposed by th e proposed injection depth require ments; 2) allows for a more

site-specific assessment of injection depth for GS projects; 3) accommodates injection into

different formation types; 4) a llows for injection of CO2 for GS into non-USDWs above and/or

between USDWs when appropriate and where it can be demonstrated that USDWs will be

protected; and 5) responds to concerns about the use of aqui fer exemptions for GS. Finally,

EPA’s approach to addressing injection depth va riability through a waiver process responds to

concerns about future drinking wa ter resource availability and the need to ensure that high

quality water remains available in sufficient qua ntities to supply drinking water needs. For

additional information on the waiver approach, pleas e see the final rule and preamble, as well as

EPA's responses to comments on the Notice of Data Availability and Request for Comment.

Letter ID: 0176 Comment ID: 23540 Letter Lines: 78 to 81

Comment Code: 3120 2.1.2 Need to identify additional confining and containment zones

(seeking comment)

Comment: being sited in what would otherwise be very safe geology. SSEB also does not

support the requirement of secondary seals for the same reason as stated above.

The only requirement would be viable provi sions for safe and secure containment

4

### to protect USDWs.

Individual Response: EPA clarifies that secondary confini ng zones are not required for all GS

sites. Rather, secondary confini ng zones are required when the Di rector determines that these

zones are needed to maximize the protection of USDWs from endangerment. EPA retains the

requirement to identify additional containment/confining zones, if required by the Director, as

proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional

confining and containment zones above the pr imary (i.e., lowermost) confining zone can

improve USDW protection. These layers could fu rther impede vertical fluid movement and

allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and

remediation. EPA disagrees that the requirement would reduce the number of sites available for

GS. The intent of this requirement is to ensure that a proposed site pr ovides adequate protection

of USDWs from endangerment; if this protection cannot be demonstrated, the Director would not

issue a permit for GS at the site.

Letter ID: 0176 Comment ID: 23541 Letter Lines: 83 to 106

Comment Code: 1250 1.1.1.4 Flexibility is needed (p erformance-based standards)

Comment: "Tailored requirements," as opposed to more general or more specific

requirements, are preferable as they provide adequate protection while

simultaneously allowing for the flexibili ty to address local geology and sitespecific conditions and to embrace evolvi ng technology. Tailored requirements

should be brought to bear when consideri ng the nine specific topical areas for

addressing the proposed Cla ss VI UIC requirements:

1. Geologic Siting;

2. Area of Review and Corrective Action;

3. Injection Well Construction;

4. Injection Well Operating;

5. Mechanical Integrity Testing;

6. Plume and Pressure Front Monitoring;

7. Recordkeeping and Reporting;

8. Well Plugging, Post-Injection Site Care, and Site Closure; and

9. Financial Responsibility and Long-term Care.

Individual Response: EPA agrees that permitting decisions for GS wells should be based on

site-specific factors. The GS ru le requires owners or operators to submit, and Directors to

5

### consider, extensive site-specific data, specified at §146.82, to demons trate that a site is suitable

for GS. Additionally, many of the permit require ments for GS wells are established through

individualized site-specific pl ans for AoR and corrective actio n, testing and monitoring, and

injection well plugging and post-injection site care and site closure. EPA adds that the final GS

rule includes a balance of speci fic criteria to be met by the owner or operator and areas of

Directorial discretion and consider ations for how that discretion would be exercised. The Agency

believes this balance allows for GS projects to be designed and permitted to address the unique,

site-specific aspects of each project, while pr oviding consistency in permitting across the U.S.

Please see the final rule and preamble for additional information on EPA's final regulatory

approach.

Letter ID: 0176 Comment ID: 23542 Letter Lines: 108 to 113

Comment Code: 4600 2.6 Proposed Plume and Pressure Front Monitoring Requirements (40

CFR 146.90)

Comment: Regarding specific points, we concur with the establishment of a threshold of a

seabed up to three miles offshore, but no farther, and we support a requirement

that the project operator should be able to demonstrate that the CO2 is

contained within the storage zone. We do not support the need to monitor the

exact location with in-zone monitoring we lls, the CO2 plume, or displace brine

pressure front. CO2 monitoring should be fit for purpose. Air and soil gas

Individual Response: EPA agrees that the owner or operator should be able to demonstrate that

CO2 is contained within the in jection zone. For this reason, the final rule, at §146.90(g) requires

owners or operators to perform CO2 plume and pressure front tracking.

The final rule, at §146.90(g), requires owners or operators to perform monitoring to track the

extent of the CO2 plume and pressure front. The owner or operator must use direct methods to

monitor for pressure changes in the injection zone. Indirect met hods (e.g., seismic, electrical,

gravity, or electromagnetic surveys and/or down- hole CO2 detection tools) are required unless

the Director determines, based on site-specific geology that such methods are not appropriate.

Pressure monitoring in the injection zone is nece ssary to track the develo pment and movement of

the pressure front and CO2 plume. When combin ed with information on temperature, pressure

data provide an indication of the phase (e.g., gas, supercritical) and distri bution of the injected

CO2 (73 FR 43515). Monitoring can also identify n eeded remedial actions, provide inputs for

AoR reevaluation modeling, evaluate predictions of plume movement, and target additional

geochemical and surface monitoring needs.

EPA disagrees that knowing the location of the plume and pressure front is unnecessary; plume

tracking and pressure monitoring are key componen ts of monitoring at GS sites. A rigorous

plume tracking and pressure monitoring scheme, such as one that meets the requirements at

§146.90(g), is imperative for ensuring that the CO2 pl ume is contained within the injection zone.

EPA clarifies that the limitation of the Class VI requirements not applying beyond the three-mile

6

### limit offshore reflects the UIC program's author ity under SDWA. See the preamble for additional

information about sub-seabed sequestration.

Letter ID: 0176 Comment ID: 23543 Letter Lines: 113 to 115

Comment Code: 4490 2.4.5 Use of tracers and potential im pact on human health or ecosystems

(seeking comment)

Comment Code: 4670 2.6.7 Surface air monitoring and/or soil gas monitoring (seeking

comment)

Comment: pressure front. CO2 monitoring should be fit for purpose. Air and soil gas

monitoring is unlikely to be beneficial, a nd the use of tracers should be at the

discretion of the owner/operator.

Individual Response: EPA acknowledges that air and soil gas monitoring to ensure USDW

protection is not necessary at a ll GS sites and agrees that the decision to use surface monitoring

and the selection of monitoring methods for th e purpose of USDW protection will be sitespecific.

The Agency believes that surface air and soil ga s monitoring, when coupled with subsurface

monitoring, may be appropriate at some GS projects to ensu re USDW protection. EPA also

acknowledges that surface air a nd soil gas measurements are subj ect to variabili ty and may not

be suitable in all settings as a method to ensure USDW protection. However, EPA does not

believe that this should entirely preclude thei r use. The decision to use surface monitoring and

the selection of monito ring methods will be site-specific (e.g., may be influenced by geology,

injection depth, and operational conditions) and must be based on poten tial risks to USDWs

within the AoR.

If surface monitoring were the only monitoring method employed to ensure USDW protection,

direct correlation of CO2 at the surface with CO 2 in the subsurface might be difficult; however,

when combined with information gathered thr ough other monitoring tech niques required of GS

well owners and operators (e.g., monitoring wells , geophysical techniques ), air and soil gas

monitoring may provide valuable data on the magnitude and location of a leak. The CO2 itself

may serve as a tracer in the form of stable is otopes of carbon. For exam ple, anthropogenic CO2

is depleted in 13C compared to naturally occurring CO2.

In the final rule, at §146.90(h), the decision to re quire such monitoring as an additional measure

to ensure USDW protection rests with the Direct or as a means of identif ying leaks that may pose

a risk to USDWs and informing emergency notifi cation of a Class VI owner or operator and UIC

Director in the event of a USDW endangerm ent, pursuant to requirements at §146.91(c).

EPA agrees that the use of tracers may not be appr opriate for all GS sites, but should be available

as an option. For this reason, EPA does not require the use of tracers at all GS sites; however, the

Director has discretion to require their use if he/she determ ines that the use of tracers could

improve monitoring of the site and enhance USDW protection from endangerment. The rule will

also allow their use if proposed by the owner or operat or and approved by the Director.

7

### Letter ID: 0176 Comment ID: 23544 Letter Lines: 117 to 120

Comment Code: 3824 2.3.1.2 Cementing of long-string casing (seeking comment)

Comment: Injection well construction de tails should be consistent with Class II CO2 EOR

experiences and operations a nd not unnecessarily burdensom e to an owner/operator

of a GS project. Continuous cementation fr om base to surface of the long-string

casing should not be required. No sp ecific timeframe for post closure care

Individual Response: EPA believes that GS is sufficiently different from Class II ER operations

to warrant the tailored construction requirements for Class VI wells at §146.86. For example, the

volume of CO2 anticipat ed to be injected in Class VI wells is significantly greater than for Class

II wells. Reservoir pressure conditions will be different, with Class VI injection operations

involving large volumes of CO2 and likely havi ng higher pressures within their storage

formations than Class II ER pr ojects. Therefore, Class VI GS reservoir pressures will increase

more in comparison to Class II ER during the injection phase of the GS project.

EPA recognizes that the oil and gas industry has decades of e xperience injecting CO2 for the

purpose of enhanced recovery and that many of th e wells used for ER may be suitable for GS.

The final GS rule, at §146.81(c), allows the cons truction of these wells to be grandfathered,

provided the owner or operator can demonstrate to the Director that the wells were engineered

and constructed to meet the requirements at §146. 86(a) and ensure protec tion of USDWs, in lieu

of requirements at §146.86(b) and §146.87(a). Only the cemented-in-place construction

requirements would be grandfathered under the fi nal GS rule; following conversion, these wells

must be permitted as Class VI wells and be subject to the operational, MIT, monitoring,

reporting, plugging, and post-in jection site care and site closur e requirements in the final GS

rule.

The final GS rule requires, at §146.86(b)(2), that the surface casing must extend through the base

of the lowermost USDW and be cemented to the surface, and that at least one long string casing

must be cemented to the surface in one or more stages at §146.86(b)(3). It does not, however,

specify how cementing must be accomplished, a nd it allows the owner or operator to propose

alternate methods that provide a sufficient amoun t of cement to meet th e standard that USDWs

are protected from endangerment. EPA notes that there are many potential ways to meet the

requirement, such as the use of staged cemen ting. Additionally, EPA is developing guidance on

the construction of Class VI wells. This guidance will be available on EPA’s website at

http://water.epa.gov/type/groundwater /uic/wells_sequestration.cfm.

Letter ID: 0176 Comment ID: 23545 Letter Lines: 120 to 122

Comment Code: 5240 2.8.2.2 Post injection timeframe (seeking comment)

Comment: casing should not be required. No sp ecific timeframe for post closure care

should be specified, and it should be based on performance standards

demonstrated by the owner/operator. Co rrosion monitoring is unnecessary, as it

8

### Individual Response: EPA agrees with commenters that th ere will be circumstances where it

can be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk

of endangerment to USDWs. For this reason, the final GS regulation offers owners or operators

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion

to shorten or lengthen the PISC timeframe during the post-injecti on period based on site-specific

data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a

Class VI well owner or operator to demons trate, during the permitting process based on

substantial data, that an alternative PISC tim eframe may be appropria te if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from enda ngerment, a default timeframe

for post-injection site care will be necessary in most cases. The default 50 year post-injection site

care timeframe represents a reasonable and prot ective monitoring period based on a review of

research studies, industry reports, and existing environmental programs, and evaluation of public

comments.

EPA believes that a default post-injection site car e timeframe of 50 years, with flexibility to

adjust the timeframe for a limited number of GS projects during the permitting process where

substantial data exists to demonstrate that an alternative timeframe would be protective of

USDWs, or based on data collected during the PISC period, is appropriate to address the range of

sites where GS is anticipated to occur, to ac commodate site-specific circumstances and various

geologic conditions, and addre sses commenters’ concerns, wh ile ensuring USDW protection.

Both approaches will utilize si te-specific data, and be based on pressure monitoring and USDW

impacts.

Letter ID: 0176 Comment ID: 23546 Letter Lines: 122 to 124

Comment Code: 4250 2.4.3 Corrosion monitoring and control

Comment: demonstrated by the owner/operator. Co rrosion monitoring is unnecessary, as it

would be assumed that compatible well construction materials suitable for use

with site-specific CO2 compos ition would be consistent.

Individual Response: EPA disagrees with commenter's asse rtions that corrosion monitoring is

unnecessary or excessive. CO2 in the presence of water (including wa ter with NOx, SOx, and

H2S impurities) can be corrosive to well mate rials and cements. Thus, although a CO2 stream

may be dry, the potential for corrosion of well materials down-hole, where the injectate can

potentially mix with water in the target forma tion, must be considered. While the construction

requirements at §146.86 were designed to protect against corrosion, EPA believes that multiple

barriers against corrosion-related failures, incl uding construction and monitoring requirements,

are necessary in order to prot ect USDWs from endangerment.

Several laboratory studies a nd a limited number of field studies have investigated and

characterized the effects of carbonic acid on well materials. La boratory studies (e.g., Kutchko et

al., 2007; Kutchko et al., 2008; Ak ervoll, 2005) consistently iden tify alterations (typically

9

### carbonation) of cement as the result of interac tions between cement and CO2-saturated brine.

Currently, there are only a few analyses of cemen t from wells that have been in prolonged

contact with CO2 in actual fiel d (down-hole) conditions. Evaluati on of cement from a well at the

Scurry Area Canyon Reef Operator s Committee (SACROC) site s howed alteration, but did not

show degradation that compromise d the structural integrity of th e cement (Carey et al., 2007). In

another study, cement samples were collected and analyzed from a CO2 production well in a

natural CO2 reservoir in Colorado exposed to a CO2-water down-hole environment for 30 years

(Crow et al., 2008). The study found evidence of reaction between the CO2-rich water and the

cement.

Oil industry research also addre sses the effects of corrosion of st eel tubing and pipes. Lopez et

al. (2003) noted that 60 percent of oilfield failures are re lated to the effects of carbonic acid from

produced brines on carbon and low alloy steels. A report by CO2 Norway (2004) notes that in

some CO2 ER floods in the Permian Basin of Texas, bare carbon steel tubing has been used

successfully.

Laboratory investigation of cement alteration/de gradation is an ongoing re search area. Few fieldbased studies have been completed to date. A lthough the laboratory and field studies currently

available suggest that corrosion pr oblems may not be serious, there is not enough data to rule out

potential corrosion problems of steel components of injection wells. Given the anticipated long

lifespan of a Class VI well and the difficulties that would be associated with a corrosion-related

well failure, EPA believes that corrosion monitoring in the down-hole environment is justified in

order to protect USDWs from endangerment.

Letter ID: 0176 Comment ID: 23547 Letter Lines: 126 to 133

Comment Code: 2046 1.5.2.3 Continuing to classify CO2 in jection for EOR/EGR as Class II/

dividing line between Class II and Class VI (seeking comment)

Comment: It is not useful to arbitrarily limit the depth of coal seams, since coal seams

store CO2 via a very different mechanism such that the required pressures are

only a few hundred pounds per square inch (psi) instead of many hundreds or

thousands of psi. The Southeast contains numerous oil and gas fields that are

potential safe geologic storage sites. SSE B encourages EPA to adopt a reasonable

process for EOR sequestration within Class II and EOR crossover to sequestration

in oil and gas fields. Oil and gas fields are proven geologic sinks and contain

much of the needed infrastructu re for efficient sequestration.

Individual Response: Regarding injection into coal seams, EPA agrees that the GS rule should

not categorically preclude or pr ohibit injection into any type of non-USDW formation. EPA also

acknowledges that there are limited circumstan ces where injection abov e the lowermost USDW

can be performed in a manner that protects US DWs. The final GS rule at 146.95 establishes a

process by which owners or opera tors can seek a waiver of the Class VI injection depth

requirements. The waiver approach requires the submission of extensive, site-specific

information (in conjunction with the permit appli cation submittal) to dem onstrate that injection

10

### of CO2 into a formation that is above or between USDWs can be done in a manner that protects

USDWs from endangerment. The requirements are de signed to ensure the owner or operator, the

Director, and the Regional Administrator consider, on a site specific basis, the implications,

benefits, and challenges associated with GS and ensuring water availability and USDW

protection.

Regarding use of oil and gas fields for GS, EP A believes that the natu re and risks of CO2

injection for long term storage is different from Class II CO2 injection for ER, and that tailored

requirements for GS wells are a ppropriate and necessary to prot ect USDWs from endangerment.

For this reason, the Agency tailored UIC requireme nts for Class VI wells that address the general

risks deep injection may pose to USDWs and specifically address the unique nature of CO2 GS

(i.e., very large volumes, very long time-per iods, and reservoir pressure conditions).

EPA is developing guidance on transitioning perm its from Class II to Class VI. The guidance

will assist Directors in determining whether an injection project should be transitioned from

Class II where the primary purpose is oil and gas production to Class VI where the primary

purpose is long-term storage of large volumes of CO2. The gu idance describes the methods

available for the Director to evaluate cha nges in risk to USDWs from projects, and

recommended approaches the Director may use to evaluate whether a project should be regulated

within the Class II or Class VI UIC program. This guidance will be available on EPA’s website

at http://water.epa.gov/type/gr oundwater/uic/wells_sequestrati on.cfm. For more information,

please see the discussion on transiti on of Class II wells in the pr eamble to the final GS rule.

Letter ID: 0176 Comment ID: 23548 Letter Lines: 135 to 137

Comment Code: 5400 2.9 Proposed Financial Respons ibility and Long-Term Care

Requirements

Comment: Finally, it is important to note that ther e are other issues, such as liability,

that are crucially important to GS and wh ich can impact GS projects, which are

not covered under this proposed rule and program.

Individual Response: EPA notes that SDWA does not co ntain any provisions addressing

liability.

Once an owner or operator has met all regulator y requirements under Part 146 for Class VI wells

and the Director has approved site closure pursuant to requirements at §146.93, the owner or

operator will generally no longer be subject to enforcement for regulatory noncompliance.

Furthermore, their financial instrument as re quired under §146.85 will be released if it was not

used. However, even if a site closure is a pproved under §146.93, an owner or operator may be

held liable for regulatory noncompliance (inc luding violation of 40 CFR 144.12) in certain

circumstances. For example, an owner or operator may be held liable for regulatory

noncompliance even after site closure was a pproved if the Direct or relied on erroneous

information (e.g., erroneous modeling data) provi ded by the owner or operator when approving

site closure.

Separate from EPA’s authority to enforce regul atory compliance, an owner or operator may be

11

### 12 subject to a §1431 response orde r even after proper site cl osure is approved under §146.93.

Under §1431 the Administrator may require an ow ner or operator to take necessary response

measures if he or she receives information that a contaminant is present or is likely to enter a

public water system or an USDW, which may pres ent an imminent and s ubstantial endangerment

to the health of persons, and the appropriate Stat e and local authorities ha ve not acted to protect

the health of such persons. Th e action may include issuing admi nistrative orders or commencing

a civil action for appropriate relief against the ow ner or operator of a Class VI well. If the owner

or operator fails to comply with the order, they may be subject to a civil penalty for each day in

which such violation occurs or failure to comply continues.

The Agency clarifies that Class VI well permits may be transferred to another owner or operator

pursuant to §144.38 whereby generally all other regulatory re sponsibilities are transferred to that

new owner and operator, which includes all poten tial liabilities associat ed with meeting the

requirements of that permit. Please see further clar ification on the issue of long term liability in

the preamble of the final rule.

Furthermore, after site closure an owner or ope rator may remain liable under tort and other

remedies, or under other federal statutes includi ng, but not limited to, Clean Air Act, 42 U.S.C.

§§ 7401-7671; CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA

does not have authority to transfer SDWA or other legal liability for Class VI wells to the State

or federal government or a third-party fund. See the final rule preamble for further discussion of

EPA's final approach.